Electric axle assembly and operating method

ABSTRACT

Methods and systems for an electric axle assembly are provided herein. The electric axle assembly includes, in one example, an electric machine with a rotor shaft having an output gear thereon. The electric axle assembly further includes a planetary gearset with a carrier coupled to a pair of axle shafts, a first ring gear with external teeth that are rotationally coupled to the output gear; and a sun gear meshing with a plurality of planet gears that rotate on the carrier, where, in the axle assembly, internal teeth of the ring gear are rotationally coupled to the plurality of planet gears, and where, in the axle assembly, the sun gear or the carrier are grounded by a housing of the electric axle assembly.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. Non-Provisionalapplication Ser. No. 17/381,050, entitled “ELECTRIC AXLE ASSEMBLY ANDOPERATING METHOD,” and filed on Jul. 20, 2021. The entire contents ofthe above-listed application are hereby incorporated by reference forall purposes.

TECHNICAL FIELD

The present disclosure relates to an electric axle with a ring gear thathas inner and outer teeth.

BACKGROUND AND SUMMARY

Electric axles have been used in vehicles due to their greateradaptability in regard to vehicle integration when compared to electricdrive arrangements that utilize electric motors and final driveassemblies which are not collocated. Performance targets such as theaxle's gear ratio and structural integrity may be at odds with spaceefficiency objectives in certain electric axle designs.

US 2021/0107345 A1 to Cooper et al. teaches an electric drive unit foran axle with torque vectoring clutches that are attached to a motorusing a structurally complex gearing arrangement. In Cooper's driveunit, the torque vectoring devices are attached to axle shafts.

The inventor has recognized several drawbacks with Cooper's electricdrive unit as well as other electric drive units. Cooper's electricdrive unit has a large number of shafts, bearings, and gears whichdecrease the unit's space efficiency and increase the unit's weight.Increased weight may be particularly undesirable in electric axles wherethe added weight contributes to the vehicle's unsprung mass whichdecreases suspension and more generally handling performance.

To address at least a portion of the abovementioned issues, the inventorhas developed an electric axle assembly. The electric axle assemblyincludes an electric machine with a rotor shaft having an output gearthereon. The axle assembly further includes a planetary gearset with acarrier coupled to a pair of axle shafts and a first ring gear withexternal teeth that are rotationally coupled to the output gear. Theplanetary gearset further includes a sun gear that meshes with aplurality of planet gears which rotate on the carrier. In the planetarygearset, internal teeth of the ring gear are rotationally coupled to theplurality of planet gears. Further, in the planetary gearset, the sungear or the carrier are grounded by a housing of the electric axleassembly. In this way, a short power path with a desired gear ratio isachieved. The weight of the electric axle can resultantly be decreasedalong with the axle's size. Because of the decreased weight and size,the axle's adaptability is significantly increased and the handlingperformance particularly with regard to suspension kinematics may beenhanced, if wanted.

Further, in one example, the sun gear may be grounded and the electricaxle assembly may additionally include a pair of torque vectoringdevices that are positioned between the pair of axle shafts and thecarrier. In such an example, the housing may enclose the electricmachine, the planetary gearset, and the pair of torque vectoringdevices. In this way, the planetary gear reduction is space efficientlyattached to the torque vectoring devices, thereby permitting the axle'stractive performance to be compactly increased.

In another example, the electric machine (e.g., electricmotor-generator) may be coaxial with the pair of axle shafts. In such anexample, the carrier may be grounded and a plurality of intermediategears mesh with the external teeth of the first ring gear. The planetarygearset further includes a second ring gear that meshes with externalteeth of the first ring gear and the plurality of planet gears.Profiling the axle assembly with coaxially arranged axle shafts and anelectric machine may decrease the space constraints that the axle poseson other vehicle systems such as the vehicle frame, suspension system,and traction battery system. Consequently, the suspension system'sperformance may be enhanced or the energy storage capacity may beincreased, if wanted.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a vehicle with an electric drive axle.

FIGS. 2A and 2B show a first example of an electric axle assembly.

FIG. 3 shows a second example of an electric axle assembly with anelectric machine and the axle shafts coaxially arranged.

FIG. 4 shows a third example of an electric axle assembly with torquevectoring devices.

FIG. 5 shows a detailed illustration of the torque vectoring devices,included in the electric axle assembly, depicted in FIG. 4 .

FIGS. 6A and 6B show different perspective views of an example of a ringgear with external and internal teeth.

FIG. 7 shows a use-case speed diagram for the planetary gearset,depicted in FIG. 2A.

DETAILED DESCRIPTION

An electric drive axle which achieves a compact design and an efficientpower path through a planetary gearset is described herein. To realizethe compactness and power path efficiency in the drive axle, a rotorshaft of an electric motor includes a gear that rotationally attaches toa ring gear with teeth on both interior and exterior surfaces.Specifically, in one example, the rotor shaft gear may directly meshwith the exterior ring gear teeth. Continuing with this example, the sungear may be grounded to a housing and the carrier serves as an output ofthe planetary gearset that is coupled to axle shafts. In this manner, adesired speed reduction and torque increase can be achieved in thegearset which increases motor efficiency. For instance, the geartrain'sratio may have a wide flexibility due to the kinematic relationshipbetween the components in the planetary gearset. For instance, when alower gear ratio is desired, the sun gear size may be increased and viceversa. Specifically, in one example, the ring gear to sun gear ratio inthe planetary gearset may be comparatively low. A low ring gear to sungear ratio allows the sun gear diameter to be increased to enable ahollow shaft connection from the carrier to a differential or torquevectoring devices. In one example, torque vectoring devices may bearranged between the output carrier and the axle shafts to permit axleshaft speeds to be independently augmented to enhance electric axleperformance. In another example, the electric motor and the axle shaftsmay be coaxially arranged. To realize this compact arrangement, a secondring gear may be included in the planetary gearset which meshes with theexternal teeth of the first ring gear and a plurality of planet gearsthat mesh with a sun gear that is attached to a differential. In thecoaxial electric drive axle arrangement, the carrier is grounded by theaxle's housing. The coaxial motor and axle shaft arrangement may poseless packaging constraints on surrounding components, such as thevehicle's suspension and energy storage systems. The vehicle'ssuspension performance and/or energy storage capacity may be increasedas a result, if desired.

A vehicle 100 is depicted in FIG. 1 with a powertrain 101. The vehiclecomponents are schematically illustrated in FIG. 1 but it will beunderstood that the components have greater structural complexity thatis expanded upon herein with regard to FIGS. 2-6B. The powertrain 101includes an electric axle assembly 102. The vehicle 100 may be a light,medium, or heavy duty vehicle. The electric axle assembly 102 includesan electric machine 104 (e.g., an electric motor-generator such as amulti-phase electric motor-generator) designed to generate motive powerand transfer said power to a geartrain 106 with a planetary gearset.Specifically, in one example, the geartrain may be a one-speed geartrainthat does not include clutches or brakes which provide gear shiftoperation. Different geartrain arrangements are described in greaterdetail herein with regard to FIGS. 2-5 . Additionally, the electricmachine 104 may be electrically coupled to an energy storage device 105(e.g., a traction battery). Arrow 107 denotes the flow of power betweenthe energy storage device 105 and the electric machine 104. In themulti-phase electric motor example, an inverter may be used to provideelectrical energy to the motor and may be designed to operate with thesame number of phases as the electric motor.

The geartrain 106 may be coupled to a differential 108, in one example,or a pair of torque vectoring devices, in other examples. Thedifferential 108, or torque vectoring devices in the alternate example,are rotationally coupled to axle shafts 110. In turn, the axle shafts110 are rotationally coupled to drive wheels 112. The axle shafts 110may be conceptually included in the electric axle.

The electric axle assembly 102 may be a front or rear axle. In eithercase, a second axle 114 may be included in the vehicle 100. The secondaxle 114 may include a differential 116 and axle shafts 118 connected todrive wheels 120. Further, as illustrated, the second axle 114 is anon-drive axle and may be steerable. However, in alternate arrangement,the second axle 114 may be an electric axle or may be coupled to aninternal combustion engine. In the internal combustion engine example,the vehicle is a hybrid electric vehicle (HEV), although the vehicle 100may be an electric vehicle (EV), in the other examples.

The vehicle 100 may further include a control system 150 with acontroller 152 as shown in FIG. 1 . The controller 152 may include amicrocomputer with components such as a processor 154 (e.g., amicroprocessor unit), input/output ports, an electronic storage medium156 for executable programs and calibration values, e.g., a read-onlymemory chip, random access memory, keep alive memory, a data bus, andthe like. The storage medium may be programmed with computer readabledata representing instructions executable by a processor for performingthe methods and control techniques described herein as well as othervariants that are anticipated but not specifically listed.

The controller 152 may receive various signals from sensors 158 coupledto various regions of vehicle 100. For example, the sensors 158 mayinclude a motor speed sensor, a pedal position sensor to detect adepression of an operator-actuated pedal, such as an accelerator pedalor a brake pedal, speed sensors at the vehicle wheels 112 and 120, etc.An input device 159 (e.g., accelerator pedal, brake pedal, combinationsthereof, etc.) may further provide input signals indicative of anoperator's intent for vehicle control.

Upon receiving the signals from the various sensors 158 of FIG. 1 , thecontroller 152 processes the received signals, and employs variousactuators 160 of vehicle components to adjust the components based onthe received signals and instructions stored on the memory of controller152. For example, the controller 152 may receive an accelerator pedalsignal indicative of an operator request for increased vehicleacceleration. In response, the controller 152 may command operation ofthe electric machine 104 to adjust actuators in the electric machine toalter machine power output to increase the power delivered from themachine to the drive wheels via the geartrain. The other controllablecomponents in the vehicle may function in a similar manner with regardto sensor signals, control commands, and actuator adjustment, forexample.

An axis system 190 is provided in FIG. 1 , as well as FIGS. 2-6B, forreference. The z-axis may be a vertical axis (e.g., parallel to agravitational axis), the x-axis may be a lateral axis (e.g., horizontalaxis), and/or the y-axis may be a longitudinal axis, in one example.However, the axes may have other orientations, in other examples.

FIG. 2A shows a first example of an electric axle assembly 200. Theelectric axle assembly 200 includes an electric machine 202 (e.g.,electric motor-generator). The electric machine 202, as well as theother electric machines described herein include a rotor 204 and astator 206 that electromagnetically interact to generate rotationalenergy. The rotor 204 rotates on a rotor shaft 208. Furthermore, theelectric machines described herein may be alternating current (AC) typemotors such as multi-phase motors. In such an example, the electricmachine 202 may be coupled to an energy storage device 210 (e.g.,traction battery) by way of an inverter 212 (e.g., a multi-phaseinverter). Arrows 214 indicate the power transfer that can occur betweenthe energy storage device 210 and the electric machine 202.

The rotor shaft 208 extends axially outward from an enclosure of theelectric machine 202. The rotational axis 216 of the electric machine202 is provided for reference. Bearings 218 may be coupled to opposingaxial sides of the rotor shaft 208. A rotor shaft gear 220, functioningas an output gear, is fixedly coupled to the rotor shaft 208 and rotatesthereon during motor operation. It will be understood that the gearsdescribed herein include teeth that are designed to mesh with teeth onan adjacent gear and facilitate power transfer therebetween.

The rotor shaft gear 220 meshes with teeth on an external surface 222 ofa ring gear 224 in a planetary gearset 227. An example of a ring gear600 with external teeth 602 and internal teeth 604 is illustrated inFIGS. 6A and 6B. The ring gear 600 specifically includes an internalsurface 606 with the internal teeth 604 and an external surface 608 withthe external teeth 602. The ring gear 600 may further include a body610. A first section 612 of the body 610 may extend away from theexternal teeth 602 in an axial direction and a second section 614 of thebody may extend radially inward towards the gear's rotational axis 616.The first section 612 may have a smaller diameter than the outerdiameter of the teeth 602. The body 610 may further include an innerextension 618 that may be coupled to a bearing. Specifically, an innercircumferential surface may mate with an outer race of a bearing. Inthis way, the ring gear 600 may be permitted to rotate in relation tothe axle's housing. By providing a ring gear with inner and outer gearengagement functionality the number of axle components such as shaftsand bearings may be reduced, if desired. In this way, the axle'scomplexity may be reduced along with the likelihood of componentdegradation. The internal and external teeth in the ring gear 600 arespecifically illustrated as straight cut teeth. However, the teeth mayhave a helical arrangement, in other examples.

Returning to FIG. 2A, one or more bearings 225 (e.g., a set of twobearings) may be coupled to the body 226 of the ring gear 224. In thisway, the ring gear 224 may be supported and permitted to rotate. Thebearing 225 may be attached to a housing 228 of the electric axleassembly 200. In particular, the bearing 225 may be attached to asection 230 of the housing 228 that extends along a motor housing 231and may attach thereto. As described herein, a bearing may be a rollertype bearing with roller elements (e.g., spherical rollers, cylindricalrollers, tapered cylindrical rollers, and the like) that are enclosed byinner and outer races.

Inner teeth of the ring gear 224 mesh with multiple planet gears 232 ona carrier 234 in the planetary gearset 227. A bearing 233 may be coupledto the carrier 234 and a section 235 of the housing 228. The bearing 233supports and enables rotation of the carrier 234. In this way, thecarrier 234 and the ring gear 224 may be allowed to rotate.

A detailed view of an example of the bearings 225 in shown in FIG. 2B.The bearings 225 are specifically illustrated as angular contact ballbearings that are adjacent to one another, to increase axle spaceefficiency. Alternatively, in other embodiments, the bearings 225 may bespaced away from one another and may have another suitable configurationsuch as cylindrical roller bearings, needle roller bearings, etc. Asillustrated, the inner races of the bearings 225 are coupled to thehousing section 230 and the outer races of the bearings are coupled to asection of the body 226 of the ring gear 224. In this way, the bearingsmay be space efficiently incorporated into the electric axle. However,other arrangements of the bearings and the ring gear may be used, inother embodiments.

Returning to FIG. 2A, the carrier 234, in the illustrated example, isrotationally coupled to a differential 236. The differential 236 may bedesigned as a planetary differential that may include a case functioningas a carrier on which two sets of planet gears rotate and mesh with twosun gears that are coupled to axle shafts. In this way, the electricaxle's compactness is further increased. However, a different type ofdifferential may be used in alternate embodiments such as a differentialwith spider gears that mesh with bevel gears, a locking differential,etc.

The differential 236 is coupled to axle shafts 238, 240. The axle shaft240 extends through a central opening 242 of a sun gear 244 in theplanetary gearset 227. In this way, the axle's compactness is increased.Bearings 246 may be coupled to the differential 236 to permit rotationof the axle shafts 238, 240.

The sun gear 244 meshes with the planet gears 232 that ride on thecarrier 234. The sun gear 244 is grounded by the housing 228, in theillustrated example. Grounding the sun gear to the housing whileproviding a ring gear with both internal and external teeth permits theaxle assembly to achieve greater space efficiency while at the same timepermitting a wide range of geartrain ratio adaptability. In this way,the electric axle assembly may have wide applicability across a largebreadth of vehicle platforms.

The housing 228 may ground the sun gear 244 by way of an axial extension248. Additionally, another housing section 250 may bolt on or otherwisemechanically attach to the housing section 230. The housing section 250may at least partially circumferentially surround the axle shaft 240.

FIG. 7 shows a use-case speed diagram for the planetary gearset 227. Thehorizontal axes indicate the speeds of the ring gear, carrier, and sungear. In particular, the ring gear speed is greater than the carrierspeed and the sun gear speed is zero due to the grounding of the sungear. A lower ring to sun (RTS) value may provide a higher ratioreduction. In one example, a lower RTS value may be used to enable thediameter of the sun gear to be increased to allow a hollow shaftconnection from the carrier to the differential (or torque vectoringdevices, in other embodiments).

FIG. 3 shows another example of an electric axle assembly 300. Theelectric axle 300 again includes an electric machine 302 such as anelectric motor-generator. However, the electric machine 302 depicted inFIG. 3 is arranged coaxial to the axle shafts 304. Therefore, in thecoaxial arrangement, the electric machine 302 includes a central openingwith one of the axle shafts 304 extending therethrough. The coaxialarrangement may increase the axle's space efficiency and pose less spaceconstraints on surrounding vehicle components such as the vehicle'ssuspension system.

A rotor shaft 306 of the electric machine 302 includes an output gear308 that resides thereon. The output gear 308 is coupled to a first setof planet gears 310 that are grounded via a shaft 312. The planet gears310 mesh with internal teeth 313 of a first ring gear 314. The ring gear314 again includes external teeth 315 that mesh with a second ring gear316. The second ring gear 316 specifically includes a first set of teeth318 that mesh with the external teeth and a second set of teeth 320 thatmesh with a second set of planet gears 322. The second set of planetgears 322 are grounded via a shaft 324 and further mesh with a sun gear326. Further, the sun gear 326 is rotationally coupled to a case 328 ofa differential 330. The case of the differential may have spider gearsthat rotate thereon and mesh with side gears 332.

FIGS. 4 and 5 illustrate varying levels of detail of another example ofan electric axle assembly 400. FIG. 4 shows an arrangement of a housingin the axle assembly 400 while FIG. 5 shows a detailed illustration oftorque vectoring devices 500, 502 in the axle assembly 400.

Turning to FIG. 4 , the electric axle assembly 400 again includes anelectric machine 402 with a rotor shaft 404 with an output gear 406coupled thereto. The output gear 406 meshes with a ring gear 408 thatincludes exterior teeth 410 and interior teeth 412. Thus, the ring gear600, shown in FIGS. 6A and 6B may be used in the electric axle assembly400. More generally, the ring gear 408 is included in a planetarygearset 414. The planetary gearset 414 further includes planet gears 416rotating on carrier 418 that is rotationally coupled to a shaft 420. Theshaft 420 extends between the pair of torque vectoring devices 500, 502.In turn, axle shafts 422, 424 are coupled to the torque vectoringdevices 500, 502.

A housing 426, depicted in FIG. 4 , includes a first section 428 atleast partially enclosing the electric machine 402. A second housingsection 430 encloses a portion of the planetary gearset 414 and thetorque vectoring device 502. Further, a third housing section 432encloses the torque vectoring device 500. Attachment device 434 (e.g.,bolts, screws, clamps, etc.) may be used to couple the housing sectionsto one another. In this way, the electric motor, torque vectoringdevices, and planetary gearset may be efficiently accessed. Housingarrangements with different profiles and partitions may be used, inother examples.

FIG. 5 shows a detailed view of the torque vectoring devices 500, 502 inthe electric axle assembly 400 with the housing omitted. The planetarygearset 414 is again shown. The torque vectoring device 500 includes afirst set of plates 504 coupled to a clutch drum 506 and a second set ofplates 508 coupled to a clutch can 510. The clutch can 510 isrotationally coupled to the axle shaft 422. The torque vectoring device500 may further include a clutch drum bearing 512 and a thrust bearing514 that permits a clutch actuation mechanism 516 to rotate. The clutchactuation mechanism 516 may be hydraulically actuated and designed toengage and disengage the plates 504, 508 in the device to permit varyingamount of torque transfer through the torque vectoring device to thecorresponding axle shaft or vice versa. Thus, the torque vectoringdevices may be designed for continuous adjustment between an openconfiguration where torque transfer from the device to the axle shaft isinhibited and a fully closed configuration where all of the torque fromthe drum is transferred to the clutch can.

The torque vectoring device 502 may be similar to the torque vectoringdevice 500 and again includes a first set of plates 518, a clutch drum520, a second set of plates 522, a clutch can 524, a clutch drum bearing526, a thrust bearing 528, and a clutch actuation mechanism 530. Each ofthe clutch actuation mechanisms 516, 530 may be electronicallycontrolled. For instance, controller 152, shown in FIG. 1 may induceactuation of the torque vectoring devices 500, 502.

The electric axle assemblies shown in FIGS. 2-5 may share some commonstructural and functional features. For instance, the electric machinesin each of the axle assemblies may have similar components.

In any of the electric axle assembly embodiments described above, amethod for electric axle operation may be implemented. The method may becarried out as instructions stored in memory executed by a processor ina controller. As such, performing the method steps may include sendingand/or receiving commands which trigger adjustment of associatecomponents, as previously indicated. The method includes transferringrotational energy from the electric machine to the ring gear of theplanetary gearset. The method may further include independentlyadjusting the speed of the axle shafts via operation of the pair oftorque vectoring devices positioned between the pair of axle shafts andthe carrier. The speed of the axle shafts may be adjusted duringcornering, low traction conditions, etc. to increase the vehicle'shandling performance.

The technical effect of the electric axle assembly operating methoddescribed herein is to increase motor efficiency via a planetary gearsetthat compactly attains a targeted speed reduction and torque increase.

FIGS. 6A and 6B are drawn approximately to scale. However, otherrelative component dimensions may be used, in alternate embodiments.

FIGS. 1-6B show example configurations with relative positioning of thevarious components. If shown directly contacting each other, or directlycoupled, then such elements may be referred to as directly contacting ordirectly coupled, respectively, at least in one example. Similarly,elements shown contiguous or adjacent to one another may be contiguousor adjacent to each other, respectively, at least in one example. As anexample, components laying in face-sharing contact with each other maybe referred to as in face-sharing contact. As another example, elementspositioned apart from each other with only a space there-between and noother components may be referred to as such, in at least one example. Asyet another example, elements shown above/below one another, at oppositesides to one another, or to the left/right of one another may bereferred to as such, relative to one another. Further, as shown in thefigures, a topmost element or point of element may be referred to as a“top” of the component and a bottommost element or point of the elementmay be referred to as a “bottom” of the component, in at least oneexample. As used herein, top/bottom, upper/lower, above/below, may berelative to a vertical axis of the figures and used to describepositioning of elements of the figures relative to one another. As such,elements shown above other elements are positioned vertically above theother elements, in one example. As yet another example, shapes of theelements depicted within the figures may be referred to as having thoseshapes (e.g., such as being circular, straight, planar, curved, rounded,chamfered, angled, or the like). Additionally, elements co-axial withone another may be referred to as such, in one example. Further,elements shown intersecting one another may be referred to asintersecting elements or intersecting one another, in at least oneexample. Further still, an element shown within another element or shownoutside of another element may be referred as such, in one example. Inother examples, elements offset from one another may be referred to assuch.

The invention will be further described in the following paragraphs. Inone aspect, an electric axle assembly is provided that comprises anelectric machine with a rotor shaft having an output gear thereon; aplanetary gearset including: a carrier coupled to a pair of axle shafts;a first ring gear with external teeth that are rotationally coupled tothe output gear; and a sun gear meshing with a plurality of planet gearsthat rotate on the carrier; wherein internal teeth of the first ringgear are rotationally coupled to the plurality of planet gears; andwherein the sun gear or the carrier are grounded by a housing of theelectric axle assembly.

In another aspect, a method for operating a one-speed electric axleassembly is provided that comprises transferring rotational energy froman electric machine to a ring gear of a planetary gearset; wherein theplanetary gearset includes: a carrier coupled to a pair of axle shafts;the ring gear with external teeth that are rotationally coupled to anoutput gear of the electric machine; and a sun gear meshing with aplurality of planet gears that rotate on the carrier; wherein internalteeth of the ring gear are rotationally coupled to the plurality ofplanet gears; and wherein the sun gear or the carrier are grounded by ahousing of the electric axle assembly. The method may further comprise,in one example, independently adjusting the speeds of the axle shaftsvia operation of a pair of torque vectoring devices positioned betweenthe pair of axle shafts and the carrier.

In yet another aspect, a one-speed electric axle assembly is providedthat comprises an electric motor-generator with a rotor shaft having anoutput gear thereon; a planetary gearset including: a carrier coupled toa pair of axle shafts; a ring gear with external teeth that mesh withthe output gear; and a sun gear meshing with internal teeth in the ringgear and a plurality of planet gears that rotate on the carrier; andwherein the sun gear is grounded by a housing; and wherein the housingencloses the electric motor-generator and the planetary gearset.

In any of the aspects or combinations of the aspects, the sun gear maybe grounded and the electric axle assembly may further comprise a pairof torque vectoring devices positioned between the pair of axle shaftsand the carrier.

In any of the aspects or combinations of the aspects, the first ringgear may include an extension supported by one or more angular contactbearings coupled to the housing.

In any of the aspects or combinations of the aspects, the housing mayenclose the electric machine, the planetary gearset, and the pair oftorque vectoring devices.

In any of the aspects or combinations of the aspects, the electric axleassembly may be a one-speed electric axle assembly.

In any of the aspects or combinations of the aspects, the electricmachine may be coaxially arranged with the pair of axle shafts.

In any of the aspects or combinations of the aspects, the carrier may begrounded and a plurality of intermediate gears may mesh with theexternal teeth of the first ring gear and the planetary gearset mayfurther comprise a second ring gear that meshes with external teeth ofthe first ring gear and the plurality of planet gears.

In any of the aspects or combinations of the aspects, the electric axleassembly may further comprise a differential coupled to the sun gear andthe pair of axle shafts.

In any of the aspects or combinations of the aspects, the sun gear mayinclude a hollow shaft with a central shaft that is coupled to the pairof axle shafts and extends through the hollow shaft.

In any of the aspects or combinations of the aspects, the output gearand the planetary gearset may be arranged on a common axial plane thatextends from a central axis of the planetary gearset.

In any of the aspects or combinations of the aspects, the sun gear maybe grounded and the housing may enclose the electric machine and theplanetary gearset.

In any of the aspects or combinations of the aspects, the electricmachine may be coaxially arranged with axle shafts; and a rotor shaft ofthe electric machine may include a central opening with one of the axleshafts extending therethrough.

In any of the aspects or combinations of the aspects, the sun gear maybe splined, bolted, and/or welded to a section of the housing.

In any of the aspects or combinations of the aspects, the electric axleassembly may be a solid beam axle.

In any of the aspects or combinations of the aspects, the electric axleassembly may further comprise a pair of torque vectoring devicespositioned between the pair of axle shafts and the carrier and whereinthe housing encloses the pair of torque vectoring devices.

In any of the aspects or combinations of the aspects, the ring gear mayinclude an extension supported by one or more angular contact bearingscoupled to the housing.

In any of the aspects or combinations of the aspects, the planetarygearset may be a single stage planetary gearset.

In any of the aspects or combinations of the aspects, the output gearand the planetary gearset may be arranged on a common axial plane thatextends from a central axis planetary gearset.

In any of the aspects or combinations of the aspects, the planetarygearset does not includes any clutches or brakes.

In another representation, an electric beam axle is provided with adrive unit that includes an electric motor, a planetary gear reductionwith a ring gear that has outer teeth meshing with an output gear of theelectric motor and inner teeth that mesh with a plurality of planetgears on a carrier, wherein the planetary gear reduction includes a sungear that is grounded to a housing.

Note that the example control and estimation routines included hereincan be used with various powertrain, electric drive, and/or vehiclesystem configurations. The control methods and routines disclosed hereinmay be stored as executable instructions in non-transitory memory andmay be carried out by the control system including the controller incombination with the various sensors, actuators, and other transmissionand/or vehicle hardware in combination with the electronic controller.As such, the described actions, operations and/or functions maygraphically represent code to be programmed into non-transitory memoryof the computer readable storage medium in the vehicle and/or drivetraincontrol system. Further, portions of the methods may be physical actionstaken in the real world to change a state of a device. The specificroutines described herein may represent one or more of any number ofprocessing strategies such as event-driven, interrupt-driven,multi-tasking, multi-threading, and the like. As such, various actions,operations, and/or functions illustrated may be performed in thesequence illustrated, in parallel, or in some cases omitted. Likewise,the order of processing is not necessarily required to achieve thefeatures and advantages of the example examples described herein, but isprovided for ease of illustration and description. One or more of theillustrated actions, operations and/or functions may be repeatedlyperformed depending on the particular strategy being used. One or moreof the method steps described herein may be omitted if desired.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevant artsthat the disclosed subject matter may be embodied in other specificforms without departing from the spirit of the subject matter. Theembodiments described above are therefore to be considered in allrespects as illustrative, not restrictive. As such, the configurationsand routines disclosed herein are exemplary in nature, and that thesespecific examples are not to be considered in a limiting sense, becausenumerous variations are possible. For example, the above technology canbe applied to powertrains that include different types of propulsionsources including different types of electric machines, internalcombustion engines, and/or transmissions. The subject matter of thepresent disclosure includes all novel and non-obvious combinations andsub-combinations of the various systems and configurations, and otherfeatures, functions, and/or properties disclosed herein.

As used herein, the terms “substantially” and “approximately” areconstrued to mean plus or minus five percent of the range, unlessotherwise specified.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

1. A one-speed electric axle, comprising: an electric machine with arotor shaft with an output gear that is coupled thereto; and a planetarygearset rotationally coupled to a differential and including: a firstring gear with external teeth that mesh with the output gear; and a sungear meshing with a first plurality of planet gears that rotate on acarrier; wherein internal teeth of the first ring gear are rotationallycoupled to the first plurality of planet gears; wherein the sun gear orthe carrier is grounded by a housing of the one-speed electric axle; andwherein the planetary gearset does not includes a second sun gear. 2.The one-speed electric axle of claim 1, wherein: the electric machine iscoaxially arranged with a pair of axle shafts that are rotationallycoupled to the differential; and one of the axle shafts in the pair ofaxle shafts extends through the electric machine.
 3. The one-speedelectric axle of claim 1, wherein teeth of the output gear mesh withexternal teeth of the first ring gear.
 4. The one-speed electric axle ofclaim 1, wherein a rotational axis of the electric machine are parallelto rotational axes of a pair of axle shafts that are coupled to thedifferential.
 5. The one-speed electric axle of claim 1, wherein theone-speed electric axle is included in an all-electric vehicle.
 6. Theone-speed electric axle of claim 1, wherein the one-speed electric axleis included in a hybrid electric vehicle.
 7. The one-speed electric axleof claim 1, further comprising a second ring gear that meshes with asecond plurality of planet gears.
 8. The one-speed electric axle ofclaim 1, wherein the housing at least partially encloses the electricmachine and the planetary gearset.
 9. The one-speed electric axle ofclaim 1, further comprising a pair of electrically actuated torquevectoring devices positioned between the pair of axle shafts and thecarrier.
 10. The one-speed electric axle of claim 1, wherein the sungear meshes with the differential and the differential is a spider geardifferential.
 11. A method for operation of a one-speed electric axle,comprising: transferring rotational energy from an electric machine to aring gear of a planetary gearset; and wherein the planetary gearset isrotationally coupled to a differential and includes: the ring gear withexternal teeth that are rotationally coupled to an output gear of theelectric machine; and a sun gear meshing with a plurality of planetgears that rotate on a carrier; wherein internal teeth of the ring gearare rotationally coupled to the plurality of planet gears; wherein thesun gear is grounded by a housing of the one-speed electric axle; andwherein the planetary gearset only includes a single sun gear.
 12. Themethod of claim 11, wherein the electric machine is an electricmotor-generator.
 13. A one-speed electric axle, comprising: an electricmotor-generator with a rotor shaft with an output gear that is coupledthereto; and a planetary gearset coupled to a differential andincluding: a first ring gear with external teeth that mesh with theoutput gear; and a sun gear meshing with a first plurality of planetgears that rotate on a first carrier; wherein internal teeth of thefirst ring gear are rotationally coupled to the first plurality ofplanet gears; and wherein the planetary gearset does not includes asecond sun gear.
 14. The one-speed electric axle of claim 13, whereinthe first ring gear includes external teeth that directly mesh withinternal teeth of a second ring gear.
 15. The one-speed electric axle ofclaim 14, wherein planetary gearset includes a second set of planetarygears that mesh with the second ring gear and rotate on a second carrierand wherein the first carrier and the second carrier are grounded by ahousing.